docs: async def add_all(self, recursive=False):
          """
          Add all handleable devices that available at start.
  
          :param bool recursive: recursively mount and unlock child devices
          :returns: whether all attempted operations succeeded
          """
          tasks = [self.auto_add(device, recursive=recursive)
                   for device in self.get_all_handleable_leaves()]
          results = await gather(*tasks)
          success = all(results)
          return success